Filtering apparatus



Jan, 19, R937.. D. Bj BANKS ET AL FILTERING APPARATUS Filed Nov. 2e, 1934 9 Sheets-Sheet l Fkx.

alm. 19, 1937. Y Ufa BANKS E1- AL 2,063,257

FILTERING APPARATUS` l Filed Nov. zes,` 1954 9 sheds-sheet 2 Jan. 19, 93?. D. B. BANKS ET AL 2,068,257

FILTERING APPARATUS Filed Nov. 26, 1954 9 Sheets-Sheet 5 a /M/f/vro/Ps Jan.' 19, i937. D. B. BANKS ET AL 2,068,257

FILTERING APPARATUS Filed Nov. 26, 1934 9 Sheets-Sheet 4 Jan. 19, 1937. D. BQBANKS ET AL FILTERING APPARATUS Filed Nov. 26, 1954 9 Sheets-Sheet 5 Milz w\ Eli VS Jan. 19, 1937. D, B BANKS ET AL 2,068,257

FILTERING APPARATUS -Ffiled Nov. 26, 1934 9 Sheets-Sheet 6 Jan.' 19, 1937.

D. B. BANKS ET Al.v

FILTERING APPARATUS Filed Nov, 26, 1934 9 lsheetssheet 7 v Jan. 19, 1937. D. B. BANKS ET AL FILTERING lAPPARATUS Filed Nov. ze, 1954 LAfro @fr/ww Patented Jan..I 19,' .1937

"l UNirEo STATES PATE-Nr v'ori-flor,

'FmrEmNG APPARATUS "Daniel B. Banks, Upper Darby, and Paul D.

Barton, Wynnewood, Pa., assgnors, assignments, to Sun Oil Company, pliia,1 a.,a corporation of New Jersey Application November 26, 1934, serial No. 154,714

` 1': claims. (01210-153) This invention relates to an improved filtering tralshaft and the'filter arms and leaves con- 4 appartus and more particularly to an improved continuous vacuum filter especially adapted for filtering chilled mixtures of mineral oil, wax, and

filter cake from .the mineral oil and propane.

Heretofore, in filtering chilled solutions of mineral oil, wax and a solvent it has been proposed to use rotary drum filters of eithera pressure-or vacuuzntype in.which the drum is par- Afilters'are not satisfactory, since in order. to obtainsufcient filtering surface, it is necessary to,` employ such a large number of 'filters tha'tthe power required to operate them'and the floor I'space occupied by them makes their operation uneconomical. Also', it is-impossible toadequately wash the filter cake by m'ea'nsiof a spray, so that a large amount of the mineral oil cannot be refilters now used when filtering a chilled mixture of oil, wax and solvent on a commercial scale.

It is therefore an object ofl this invention to 3 provide an improved filtering apparatus which is especially adapted to the continuous vfiltration of chilled miicturesof oil, wax and a solvent.

It is a further object'of thiswinvention to pro' vide such a filtering apparatus which requires al minimum of space and which requires a minimum of power to-operate. y

It is a further object of this invention to proy videsuch a filtering apparatus in which the filter cake lwill be thoroughlywashed by being completely submerged'in the washing fiuid.

Other andv further 'objects will be apparent to one skilled in the art, on reading this specification and on reference to the drawings attached thereto.

We have discovered that very good results may be obtained by using ordinary leaf filters and that sufficient filtering surface may be obtained by arranging these'leaf filters in the m'anner disv closed in this specification. Briefly stated then', the apparatus disclosed and claimed in this application consists of a vertical cylindrical tower, within which is arranged a multiplicity of superimposed annular trays divided into three sections, (filtering, washing, and cake removing). 4Suspended within the tower is a central shaft, to which the filter leaves are connected by filter propane. to separate -the wax`in the form of a tially submerged in the mixture to be filtered, the- For large commercial installations, however, suchA covered therefrom andis therefore lost. There are a numberof other objections vto any of the by mesne.

Philadelarms; means being provided for rotating the cennected thereto. The mixture to be filtered is admitted to the filtering sections of the trays and wash fluid is admitted to the wash sections of the trays. .Means are. provided for lifting the filter arms and leaves from one section of the trays to .the next; and a rotary valve is provided where- -by suction may be applied'to the filter leaves,

through collecting pipes in the central shaft and V the filter arms, while said leaves are in `the filtering and washing sections of the-trays, and pressure applied to said filter leaves while theyare in filter cake removal position.-

Referring now'to the drawings which are attached hereto, and which form a part of this specification, and in which like numbers refer to like parts throughout:

' Fig. 1 is a -diagrammatic representation of a4 filter built acordingjto this invention, showing the iiow thereto; o

l Fig. 2 is vertical section 'through the filter;

Fig. 3- is a section taken 'on the line 3 -3 of Fig. 4 is a detail, partly in section, of the suspension means'and drive means of the lter; l Fig. 5 is a detail, partly in section, showing the filter arms and the meansfrof suspending the same; I

Fig.'6 is a'detail, partly broken away, showing the .nieans for connecting the filter arms to` the f suspension means;

Fig. 7 is vertical section showing'jthe means for connectingthe filter arms to the collecting pipes located in the central shaft;

Fig. 8 is a section taken on the line 8 8 of Fig. 7

` Fig. 9 is a horizontal section showing the means for connecting the -filter arms to the collecting pipes located'A in the central shaft;

Fig. 10 is a detail partly in section showing the method for attaching the lter leaves to the filter arms; f,

Fig. 11 is a detail View showing a filter leaf with the filter cloth removed; f Fig. 12fis a section taken on Fig'. 11;

Fig. 13 is a section Fig. 111;

Fig. 14 is a vertical'sectionof the valve assem- 'the une n n' of taken on the line l3- |3 of bly at the bottom of the central shaft;

Fig. 15 is a detail View looking up at the top half of the valve shown'in Fig. 14;

Fig. 16 is a section taken on'the line 'I6- I6 of Fig. 14;

Fig. 17 is a detail, partly in section, of the suspension bearing for the central shaft; and

Fig. 18 is a development of the cam track for raising an'd lowering the filter leaves over the partitions in the trays. l

Fig. 19 is a vertical section of a modified form of `valve assemblyfat the bottom of the central shaft, showing `a positive mercury seal between the two halves of the valves. f

Referring now to Figs. 1 and 2, the-solution to be filtered is introduced through pipe 2 to a surge tank 3. From this surge tank the mixture is withdrawn through pipe 4 vand valve 5, by pump 6, and forced through pipe 1 and valve 8 to be introduced to the'ltering section of the top tray of the tower. The mixture Viiows down through the filtering sections of the .trays and any excess thereof is withdrawn through pipe 9 and-valve I to the surge tank 3. A pressure equalizing line |I, having valve I2 therein connects the surge tank to the interior of the tower I and equalizes the pressure between these two. The wash fluid is introducedv to the wash section of the top filter tray of the tower through line |3- having valve |4 therein and ows downwardly through the washing sections of the trays and any excess .Wash uid is withdrawn through line I having valve I6 therein. The filter cake is removed through fiume |1 and is forcedby pump |8 through line I9 to a suitable tank.

Referring more particularly to Fig. 2, the vertical tower consists of a cylindrical casing'20'-, having a closed top 2| with suitable safety valves 48 therein, and bottom 22. tower are a multiplicity of superimposed annular trays 23, there being preferably about ten of these trays in each tower. inforced by members 24 and suspended therefrom is a central vertical shaft 25. This shaft is suspended by a bearing indicated generallyas 26 and which will be described more in -detail hereafter. Attached to the 'central shaft near the top thereof is a large drive wheel 21 driven by a small pinion gear 28 on shaft 29 which is driven by. any suitable source of power. A multiplicity of filter 1eaves30 are arranged within each of the filter trays 23. These filter leaves are connected by means of filter arms 3| through b'alland socket joints 32 to collecting pipes 33 arranged within the central shaft 25, as will be explained hereafter4 more in detail. I'here are preferably about five filter leaves attached to each filter arm, and preferably about 116 radial filter arms extending from the central shaft at the level of each tray.

Each`of the annular trays 23 is-divided into three sections, a filtering section, a wash section and a lter cake removal section, by partitions 43a, 43h and* 430: Suitable downcomers 44a are provided between the lltersections of the adjacent trays, s o that the mixture to ne mte'red, which is'introduced into the top tray, may ow downwardly through the trays, any excess mixture being removed from the bottom tray through line 9. Similar downc'omers 44h are providedbetween the wash sections of adjacent trays so that the wash fluid which is introduced in the top tray through line I3 may How downwardly ,through the trays, any excess wash 'fluid being removed from the bottom tray through line I5. The filter cake removal section of thel trays has an inclined bottom 45 discharging to wax chute or flume I1.

- -Attached t'o the central shaft are spiders 34 which rotate with the shaftvand by means of Arranged within the The top of the tower is re- I removable cover plate 50.l

'The main ldrive wheel 2 1 is .connected to ring guide members 35 cause rotation of the filter arms and filter leaves attached thereto. Top spider 34 is suspended from the central shaft by rods 36 and the lower spiders are suspended from one another by staggered rods 31. The filter arms 3| are 'suspended from suitable "lifting arms 38 by rods 39.

Near the top of the tower, mounted on supporting framework 40, is a circular track 4| on which wheels 42 of the lifting arms 38 travel. Track 4| is in the form of a cam and as the lifting arms 38 are rotated by arms 14 depending from drive wheel 21,- the cam track 4| raises and lowers each lifting arm thus raising and lowering the filter arms and leaves connected thereto through rods 39- as they come to the partitions dividing the tray 4mechanism 41 more fully described in connection with Fig. 14.

The suspension means for'the central shaft and the drive means therefor is as follows: Connected to the reinforcing framework 24 at the top of 'the tower 2| is a collar 49, (Figs. 2, 4, and 17) closed at its upper end by removable plate 50. A ring 5| is seated in this collar and the head 52 of shaft 53 rests thereon.. Bearing race 54 is held on the lower end of shaft 53 by nut 55 which is keyed tothe shaft 53. A pipe 56 is Welded to the central shaft 25 -near the top thereof and is connected to member 51 by bolts 58., A bearing race 59 is held in a channel near the bottom of member 51 and roller bearings 60 are placed between bearing races 54 and 59, thereby supporting the central shaft 25 from shaft 5 3. Roller bearings |5| held between bearing r'ace I6 I on stub shaft. 53 and race |62 on member'51 act as guide bearings between said shaft 53 and member 51. It

is to be noted that the spherical shaped head 52 of shaft 53 whichbears against ring 5I forms a fsort of universal joint', thus properly Supporting pendiular.

A cupshaped memberl (Fig. 4) fits within the top of,` the cent'ral vertical shaft 25 and closes central shaft 25 even in case it is not exactly perthe opening between the shaft :25 and memberA 51 when the bolts 58 are drawn up. Bearing 60 and guide bearing |5| are lubricatedl by introducing lubricant through line |52 extending through removable cover plate 50. 'I-he lubricantv collects around the head 5 2 ofshaft 53 and drops through openings |63 therein to bearings I5I,

the lubricant then fiows down the space b etween K shaft'53 and .member 51, and ows over bearing 60, collecting in cup |50 and being removed there-A from through line |64 extending through hole |53, drilled longitudinally through shaft 53, and through lineI54 connected to linef.|64` through 56 and to member 51 by the bolts 58. Gear segments 6| are bolted to the main drive wheel 21. v

Gear 6| is driven by pinion 28 connected to shafi 29. This shaft 29 is supported by bearings 62 2,068,257. the top of the tower 2| through packing member 64, and is driven by any suitable means.

Sixteen radial lifting arms 38 are connected to the vertical shaft 25 by means of the collar 65 which is bolted to ring 66 welded to the vertical shaft. The collar 65 has bearing hooks 61 which support. pins 68 extending between plates 69 which are welded to the lifting arms 38. The supporting rods 36 for the top spiders 34 are also connected to the collar 65 as shown in Fig. 4.

A casting |55 in which stub shaft 10 is held by nut |56 is attached to the outer endof each liftngarm 38. The'wheel 42 which runs on cam track 4| is mounted on the outer end of shaft 10 by bearings .1|. On the inner end of shaft 10, in the open box in casting |55, is a guide wheel 12 mounted on shaft 1'0 by bearing 13. Guide fingers 14 are attached to main drive wheel V21 and eX- tend downwardly to spiders 15 connected to the center shaft 25. The' guide wheel 12 rotates against bearing surfaces 16 on guide fingers 14, when the lifting arms 38 are being raised or lowered. The lifting rods 39 which support the filter arms 3| are connected to the casting 4|55 by clevis 11 and pin 18.

Referring now more particularly to Figs. 5 and 6, and the assembly of the lterarms, the sixteen collecting pipes 33 are arranged within the central shaft l25 (as shown in Fig.3). These collecting pipes 33 are spaced from the central shaft: 25 by means of small spacers 19 welded to the collecting pipes. Slightly above the. level of each of the annular trays there is an opening in the central shaft 25 through which a nipple 80 extends from the` collecting pipe 33. The outer end of nipple 80 -is connected to a socket joint 8|. A plate 82 .covers the openings in central shaft 25 and is held against the central shaft'by spring 83 pressing against the socket 8| and plate 8 2 thereby permitting expansion collectingA pipes`33. A ball joint 85 -is connected to socket 8| and filter arms 3| are connected thereto. `The filter arms 3| are connectedy to lifting rods 39 as shown in detail in Fig. 6. A lug 86 is welded to the filter arm 3| and pin 81 connects this lug to clevis' 88 at the top of the lower lifting rod 39, and to links -89 which are connectedby means of pin 90 to the bottom of the upper lifting rod 39.

Spiders 34.are connected to the central shaftA 25 by being bolted to a. ring -92 which is welded to the central shaft. Vertical guides 35 are bolted f to the outer edge of spiders 34 and serve to drive the filter arms- 3| as the shaft 25 is rotated, these guide membersalso operating as vertical guides when the filter arms with guide shoe 35a are being raised or lowered. The filter leaves 30 are connected by nipples |04 to collars 93 which are slipped over the end of filter arms 3 I, as shown in Figs. 5 and 140.v A collar 94 is weldedto the lter arms 3| and theends of filter arms 3| are closed by pin .welded in the end thereof. Suitable packing 96 is provided between adjacent headers 93 and collar 91 is slipped over the end of filter arm 3|, and is keyed to pin 95to prevent any rotation of collar 91 and drawn up thereon by nut 98 on pin 95.v Holes 99 are providedin the filter arms 3| over ca h 4of the filter leaves 30. A rod |00, passingv through collar '94 and slots in the top of collars 93 and screwed intol collar 91,

prevents any rotation of collars 93 and .tlg filter leaves 30 attachedther'eto, as shown in Fig." l0.

The adjacent spiders-34 are suspended from one y Aand connected thereto by ing ||0 seals the joint between )Branch of T` ||4 leads to pipe and contraction of connection 9| at `valve mechanism and a spring' against collar |26 on b olt |24 and bearing the lower half |22 of the f connected to line in detail in Figs. 10 to 13'inclu'sive. The filter leaves consist of a frame |0|l (shown in Fig. 1l), a'collecting groove |02 'being provided in the bottom of each frame and a pipe |03 leading from groove |02 through connecting nipple |04 to headers 93. A light framework `of perforated metal strips |05 is arranged within the framework |0|. A covering of wire mesh is fitted in groove |06 in the frame |0| as shownin Fig. 13. A filter cloth in the formof la tube is slipped over the frame and is connected thereto .by forcing the lter cloth into grooves |01 around the top and bottom of frame |0| by means of a packingcord. If desired, the. bottom groovev |01 in the frame |0| may be omitted, and a filter cloth in the form of a bag closed at one end, slipped over the frame forcing the filter cloth into groove |01 at the top of frame |0| by means' of a packing cord. Referring now more particularly to Figs.` 14

to 16 inclusive, showing the valve mechanism at the bottom of.ve`rtical shaft v2 5. A cap |08 is welded to the bottom of the `central shaft 25` rounds cap 08 and is bolted to a ring Iw'ellde to the bottom 22 'of thetower I". .Suitable packcap' |08 andcollar .|09 being held in place by packing gland Each of the collection' pipes 33 into an opening in the bottom fcap; |08jwhich register with corresponding openings: ||,2` in Each opening. ||2 `is connected to a T ||4.A A sample pipe ||5 having valve H6. thereinfleads from one Abranch of the T' ||4'. The ,other ||8 therein, pipe'||1 being connected to open-i` ings ||9 in the member ||3. rI he member ||3 is bolted to the upper half |20 of the rotary valve' mechanism, openings |2| in member |20 registering with openings ||9 -in member ||,3. Openings |2| at their bottom assume the'shape of elongated slots. 'I'he lowerhalf |22 of the rotary valve mechanism presses against'the upper half '|20 of the valve and an oil seal groove |23 is provided between the twoedges of the valve. A bolt |24 is attachedto the'upper half of the |25 pressing.

which presses against valve `mechanism holds the lvalve members in alignment. Cap |58 attached to lower half |22 of the valve preventsany air being admitted tov thefiltrate or used wash fluid throughthe opening through which bolt |24 passes. half of the valve mechanism is provided with three openings, a filtrate outlet, |28, which is |29 through which the filtrate is withdrawn from thefilter, a wash fluid outlet |30 which is connected to pipel |3| through which the used wash fluid is withdrawn from the filterand a blow opening |32 which is'connected to pipe |33 through which gas under pr'essure, for blowing the filter cake from the filter leaves, is admitted to the filter. The lines |29 and |3| may be made of some flexible material, not affected by oil or cold, which is reinforced by wire spirals, or they may be metal pipes provided with ball andv socket joints.

Lower half |22 Aof the valve mechanism is con- 70 nected to the yokev |34 bypins |35, a clearancem of about an eighth of an inch being left between yoke |34 and the lower half |22of the valve, and between yokev |34 and the heads'of pins |35. Yoke |34 is connected to pin |36 which is 4is rolled A ||1 having valve" The lower n;

projections |39 inmember |38l slide in grooves |40 in framework I4I which is pivotally supyported Aon uprights |42 by pins |43. A worm gear. -I44 having handwheel |45 is provided in 'frame I 4|and by means of gear segment |46 connected to member I 38, the lower half |22 of'` the valve mechanism maybe rotated to adjust the time of applying suction or pressure to the lter. Counterweights |41 are placed on frame I4I so that none of the weight of the lower half- |22 of thevalve mechanism and connections is borne by spring |25.

Since one side of the lower half |22 of the valve mechanism will probably be heavier than the .other side, due to the outlets from filtrate opening |28 and wash fluid opening |29 being loweh half |22 of Fig. 14) is pressed against the upper half thereof by springs |25 which presses against collar |26 (Fig. 14) on bolt |24, attached to upper half 220 of the valve mechanism, and bearing |21 which presses against the lower half 222 of the valve mechanism. The lower half 222 of the valve mechanism (shown in Fig. 19) is provided with a filtrate outlet 228, a wash fluid outlet, and a blow opening; and suitable valve adjusting mechanism as shown .and described inr connection with Fig. 14 is also provided. A ring |66 supporting cup |61 isbolted to the upper edge of lip I1I forming a deep annular groove 223 on the lower half I 22 of the valve mechanism, said annular U- or J--shaped cup |61 being welded to ring |66 by a continuous weld. A ring |68 is bolted to upper half 220 of the valve mechanism and cylindrical sleeve |69 is welded thereto by a continuous weld. This sleeve extends well towards the bottom of the U-shaped portion of annular cup |61 and Well below the surface of a bath of mercury maintained therein. Small openings permit any liuid, which leaks past thejoint betweenl the two halves of the valve to drain into the filtrate outlet |28.

Due to the vacuum in the ltrate outlet, the

' 'mercury will rise in the space between the innerv wall of cup |61 and sleeve |69 until there is a column of mercury equal to the vacuum being applied. Thus, if the filter is operating under a vacuum of ten inches of mercury, there will be a ten inch column of merury between cup |61 and sleeve |69. These elements should be made long enough so that there may be a iifteen inch column of mercury in order to care for any short periods of unusually high vacuum. If necessary, dueto the extremely low temperatures at which these lters are sometimes operated, a.

suitable steam or electric heating coil (not shown) may be placed around the cup |61 to keep the mercury in liquid form. From the above description it is apparent that cup |61 remains stationary with lower half 222 of the valve mechanism while sleeve |69 rotates with upper half 220 of the valve mechanism, while the mercury forms a. positive seal between the and Valve 8 to the top tray in the tower I.

2,068,257 free to slide in opening |31 in member I 38. Two

two halves of the valve mechanism and prevents any air being admitted through thejoint between upper half 220 and lower half 222 of the valve.

The operation of the filter is as follows: A

chilled mixture of oil, wax, and propane, prepared in any suitable manner used in propane dewaxing of hydrocarbon oils, is introduced through pipe 2 to surge tank 3., This mixture is withdrawn continuously from surge tank 3 through line 4, valve 5, and pump 6, and is introduced through line 1 The line 1 preferably enters the tower I somewhat above the fluid level of the top tray. This line terminates in a head |51 on the inner side of casing which deects the solution, which is being introduced to the tower, so that it will flow down the sides thereof into the ltering section of the top tray. The solution to be filtered iills the top tray until it comes level to the upper end of the downwardly through the trays until all the trays are filled. Any excess of the solution to be filtered is withdrawn from the bottom tray through line 9 and flows into the surge tank 3. The system is so operated as to maintain a continuouscirculation of solution from the surge tank to the top tray and from the bottom tray back to the surge tank. This serves to maintain a xed liquid level in the trays as long as an excess quantity is circulated. If desired, outlets may be provided for line 1 to a number of the trays.

At the same time, wash fluid, such as chilled propane, is admitted in a similar manner to .the wash section of the top tray through line I3 and completely fills the wash section of the top tray until the level of wash fluid therein rises to the top of the downcomer 44h in the top tray. The wash iiuid then iiows down the downcomer 44h and iills the wash section of the next lower tray, and continues in the same manner downwardly through the trays until the wash section of each of the trays is lled withwash fluid. A'ny excess wash fluid is removed from the lowermost tray through line I5 and may be recirculated. 'I'he mixture to be ltered and the wash iluid are continuously, charged to the tower through lines 1 and I3, as long as the filter is in operation.

When the filtering and washing sections of the various trays have been filled and circulation between the surge tank and the filtering sections of thev trays has been established, rotation of the main shaft is started by means of pinion 28 and large gear 21. This rotation causes the filter leaves to travel through the trays in a clockwise direction (Fig. 3). vA vacuum is then applied to filtrate withdrawall line I 29 and Wash liquid withdrawal line |3I. This Vacuum causes the solution within the filtering sections of the trays to be drawn through the filter leaves and the wax to be deposited thereon in a cake. By reference to Fig. 3 it will be noted that six sets of ltering leaves are in lterin'g position while one set is being lowered into the solution for filtering and another set is at partition 43h between the ltering and washing sections. As each vertical bank of filter leaves, operated by any one of the lifting arms 38, arrives at the end of the filtering section of the trays, adjacent partitions 43h, the roller 42 at the end of the lifting arm 38 meets with a rise in the cam track 4|.

Further rotation of shaft 25 i cal bank of filters is passing through the filtering each vertical bank, is in open communication with the lifting arm 38 of each vertical bank of filters wardly, thereby lifting arm 38 and consequently through lifting rods 39 the filter leaves on each of arms 3| directly beneath. The rise in the cam track (Fig. 18) is sufficient to lift the filters clear of therpartition 43h. The filters are then lowered lat the other side of the partitions 43b into the washing sections of the trays. While each vertisection, the pipe 33wit'hin the central shaft 25, which is connected to each of the filter arms 3| in the lower half vof the outlet valve at the bottom of the filter. The filtrate is therefore constantly flowing out through line |29 due to the vacuum placed thereon. As each vertical bank of filters is raised from the filtering section and is lowered into the washing section, the port I2I which is in communication with that section is closed by the partition between openings |28 and |30 in the lower half |22 of the outlet valve. As soon as each vertical bank of filters is lowered into the washing section the port |2| in the upper half |20 of the outlet valve is placed in communication with opening |30 in the lower half of the valve and wash liquid outlet |3|. Each vertical filtering section passes through the washing section of the trays until it arrives at partition 43e at which time its port |2| in the upper half |20 of the outlet valve will be closed by the partition between opening .|30 and opening |32 in the lower half |2201" the outlet valve. As soon as each vertical section has been raised by its lifting arm 38 to a position above the wax outlet chutes 45, its corresponding valve orifice |2| will be in open communication with gas under pressure admitted to the space |32 in the lower half |22 of the outlet valve. The gas under pressure causes a distention of the filter cloth on each of the lter leaves 30, thereby causing the wax cake to break and fall off on to the chutes 45 and thence down wax flume I1. If desired the filter leaves may be maintained in open communication with wash liquid outlet |3| while being raised from the washing solution in order to permit washing fiuid remaining in pipes 3|, 33 and the lower valve mechanism to drain off into line |3| before admitting gas under pressure to these lines for the purpose of removing the'wax cake. It is preferable, however, to make pipes 3 I, 33, and the valve connection of such size that they will not be filled with the washing liquid while in the washing portion of the cycle. By such provision the washing liquid at the end of the cycle would merely be flowing down the walls of the pipe 33 and the lower valve connections and would not interfere with the upward passage of the gas for wax cake removal. As each vertical bank of filters passes from the wax removal stage, it is lowered by means of cam track 4| roller 42 and arm 38 into the solution to be filtered, and the cycle repeated.

With the valve shown in Fig. 16 and a cam track as shown in Fig. 18,'the pipe 33 which is connected to each of the filter arms 3| in each vertical bank comes into open communication with the opening |28 in the lower half of the outlet valve when the lifting arm 38 of each vertical bank arrives at the point marked A on the the opening |28 in cam track 4I (Fig. 18), and continuesv in such open communication until the lifting arm 38 arrives at the point marked B. While the lifting arms 38 of each vertical bank of filter arms'is moving from point B to point C, the port |2| which is in communication with that section is closed by the partition between openings |28 and |30 in the lower half |22 of the outlet-valve. As

passes point C, the port I2| connected to that bank cornes into communication with the opening |30 in the lower half |22 of the outlet valve and continues in communication therewith until the said lifting arm 38 reaches the point D when the said port |2| is closed by the partition between opening |30 and opening |32 in the lower half |22 of the outlet valve. As soon as the lifting arm 38 of each vertical bank of filters arrives at the point E, its corresponding' valve orice I2I will be in open communication with the space |32 in the lower half |22 of the outlet valve and will continue in communication therewith until the said lifting arm 38 arrives at the point F on the track 4|, at which point the corresponding port I2I will be closed by the partition space |32 and opening |28 in lower half |22 of the outlet valve, and

'said lifting arm 38 again arrives at the point A drawal line; however, we have here illustrated the preferred embodiment in which the filtrate is kept separated from the used wash fluid.

In case the filter cloth on one filter becomes loose or broken, wax will begin to appear in the filtrate obtained in line |29. In such case samples may be withdrawn from sample pipe I I5 by opening valve ||6 and it can thus be determined from which vertical bank of filter arms the poorly filtered material is coming. The damaged bank can then be shut off by closing valve ||8 connected to this bank, and the operation continued with the other 15 banks of filters until so many filter cloths become clogged or damaged that a good filtering rate is no longer obtained.

The exact point at which suction is applied to the filter leaves can be varied slightly by rotating the lower half |22 of the valve mechanism, by rotating worm gear |44 and thus rotating gear segment |46 and yoke |34 connected thereto'.

It is apparent from the above description that only the top half |20 of the rotary valve mechanism rotates with the central shaft 25, the bottom half of the valve mechanism |22 remaining fixed except on rare occasions when it is necessary to vary the point at which suction or pressure will be applied to the filter leaves. However, it is apparent that, in case of any eccentric rotation of the central shaft 25, the lower half |22 of the valve can move about by sliding on pins |35 and by pinv |36 sliding in and out in member |38, so that vthe upper and lower halves of the valve are always held tightly together. The fiuid which is placed in groove |23, to seal the joint between the upper and lower halves of the valve, is preferably some of the finished product obtained from the filtrate. The proper level of sealing fluid may be maintained in groove |23 by any well known means, such as by providing a large reservoir in which the proper level is maintained by a fioat valve, and connecting the reservoir to the groove |23 with suitable piping.

The cam track 4|, which raises lifting arms 38 and filter arms 3|, is so designed that as one vertical bank of filter arms is being raised over a partition in the trays the preceding vertical will continue to be closed thereby until the next section of the trays.

' the tower as a unit. The collection pipes 33 ex- 6= 'aoesfasv bank of the filter arms is being lowered into the In this manner very little poweris required to raise and lower the filter arms, the`main requirement for power being to overcome frictional resistancestwhich, however, are very small dueto the fact that the central shaft is suspended from roller bearings.' Since Ythe central shaft makes one complete rotation inthe order -of two'minutes, the filter leaves are moved very slowly' through theI liquid in the trays and therefore offer very little resistance to rotation.

The collection pipes 33 may be removed from the filter by jacking up the central shaft, removving bolts 58 and then lowering the central shaft until ring |48 rests on beams |49. The cover plate 50 is then removed and the bearings associated therewith may then be lifted through the top of tend well towards the top of central shaft 25, being suitably wired together to prevent vibrations, and are closed at their upper ends by eye bolts i60.v Each of nipples '80 is disconnected from socket joint 8| and the lower ends of pipes 33 are removed from cap |08. Cap |50 is removed and the collection pipes 33 can then be removed through the top by lifting eye bolt |50.

The mixture of oil, wax, and propane which is admitted to the filter section ofthe trays is chilled to preferably about 45 F., and consists of about 1 part of wax distillate, which may contain 16% or more of wax, to 41/2 to 5 parts of propane. At this temperature the wax will have been solidified 35. and will be held in suspension, in the oil and propane, ithe form of finely divided crystals. We preferably charge a chilled mixture of oil, wax,

asphalt, and propane obtained by refrigerating the mixture of mazoot and propane as described in Padgett and Stearns application Serial No. 733,108, filed June 29, 1934.

'I'he wash fiuid is preferably liqueed propane which has been chilled to about 45 F. At this temperature the pressure inside the filter tower will be approximatelyA atmospheric. vA suction of 10 of mercury is preferably maintained on lines |29 and I3 and gas under 5-30 pounds pressure is admitted through line |33.

While this invention has been described as being., particularly suitable for filtering chilled mixture of oil, wax and a solvent, it is apparent that it may be used to good advantage -in other' filtering operations.

It is further apparent that many modifications and changes may be made in the apparatus disclosed and claimed in the application, without departing from the spirit and scope of this invention. k l

What we claim and desire tov protect by Letters Patent is as follows:

j 1. In a filter the combination which comprisesy a closed vertical cylindrical tower; a multiplicity of superimposed annular trays arrangedwithin said tower; said trays'comprising. a filtering section, a washing section anda filter cake removal section; means for-introducing the mixture to be downwardly from'the washing section of one tray to the corresponding section of the next lower tray; means formaintaining the desired liquid level in the filtering and washing `sections of each of said trays; a multiplicity of filter leaves arranged in eacl".l of said trays; means for rotating said filter leaves around saidtrays; means vfor raising said` filter leaves over the divisions between said sectionsof said trays; means for apply# in thefiltering and washing sections of said trays; and means for supplying a gas under presaligned radial filter arms extending from said shaft at the level of each of said trays; a drive wheel for rotating said central shaft; means for driving said drive wheel; spiders attached to said central shaft; means on said spiders for rotating said `filter arms while permitting free vertical movement of the arms; a multiplicity of radial lifting arms extending from said central shaft near the top thereof; said lifting arms being the same in numberV as and vertically aligned with said filter arms; a track having raised portions thereon over the divisions between the various sectionsv of said trays, and concentric with said tower near the top thereof; wheels on said lifting arms adapted to run on said track; means for driving said lifting arms from said main drive wheel to rotate the. same with said central shaft While allowing free vertical movement of the same;l means for connecting each of said lifting arms with each. of said filter arms, vertically aligned therewith; means for introducing a mixture to be filtered to the filtering section of each of said trays; means for introducing wash fluid to the washing section of each of said trays; means for removing filter cake from the filter cake removal section of said trays; means for applying a vacuum to said filter leaves while the rsame are in the filtering and washing sections of said trays and means for supplying gas under pressure to said filter leaves while the same are in filter cake removal position.

3. In a lter of the class described, means for f suspending a central longitudinal shaft in a closed vertical cylindrical tower; said means comprising a. supporting framework in the top of said tower; a supporting ring held by said framework; a short vertical shaft having an enlarged head thereon supported by said supporting ring; a collar surrounding saidshort shaft; a bearing race on the lower end of said short shaft; a bearing race on the lower end of said collar; roller bearingsbetween said bearing races supporting said collar from said short shaft; a guide bearing ing a vacuum to said filter leaves while they are between the upper end of said short shaft and saidcollar; and means for connecting a central longitudinal shaft to said collar. y 4. A filter comprising a closed tower, a series of superimposed annular trays therein, each of said trays having partitions dividing it into arcuate filtering, washing, and' filter cake removing sections, a multiplicity 'of filter leaves in each of said trays, means torotate said leaves around the trays, means for lifting said filter leaves over the partitions in said traysgmeans through which liquid `filtered through the leaves is adapted to be withdrawn, means to introduce the mixture to be filtered and the washing liquid to the t'opmost .ried by the tubes titions.

ber to -through the leaves is adapted to be withdrawn,

arms, rotating with the shaft, above the series of trays, tube-lifting members Adepending from' said arms and engaging said tubes, and means, operable in the rotation of said arms, to lift them at intervals and thereby lift said tubes to cause the filtering leaves carried thereby to clear' said partitions.

6. A filter comprising a closed tower, a series of superimposed annular trays therein, each of said trays having partitions dividing it into arcuate filtering and filter cake removing sections, a rotatable upright shaft extending through the tower, a multiplicity of filter leaves in each of said trays, a multiplicity of tubes carrying the lter leaves of each tray and rotatable with the-shaft, and through which the liquid filtered'through the leaves is adapted to be withdrawn, a multiplicity of filter leaves in each of said-trays, means to rotate said leaves around the trays, means through. which liquid filtered through the leaves is adapted to be withdrawn, the leaves of the series ofAv trays being arranged in vertical alignment, and leaflifting means adapted, during the rotation of the leaves, to lift successively all the leaves ineach tray to cause them to successively clear the partitions therein and to lift simultaneously vertically aligningleaves in the series of trays.

7. A filter comprising a closed tower, a series of superimposed annular trays therein, each of l said trays having partitions dividing'it into arcuate filtering and filter cake removing sections, a

rotatable upright :haft extending through the tower, a multiplicity of filter leaves in each of said trays, a multiplicity of tubes carrying the filter leaves of each tray and rotatable with the shaft and through which the liquid filtered through the leaves is adapted to be withdrawn, arms, rotating with the shaft, above the series of trays, tube-lifting members depending from said arms and engaging said tubes, 'a circular c'am' track upon which the outer ends, of such arms travel and which is adapted to lift such arms at intervals and thereby lift said tube-lifting members to cause the filtering leaves carto be lifted to clear said par- 8. A- filter comprising a closed tower, a seriesy of superimposed annular trays therein, a rotatable upright shaft in the tower, a multiplicity of filter leaves in each of said trays, a Series of sets of tubes, each set, of leaves in one of the trays, and throu'ghwhich the liquid filtered by the leaves is adapted to be withdrawn, a number of vertical pipes withiniand rotating with' theshaft and with-which the tubes of each set communicate, liquid outflow channels at the bottom of the shaft/,corresponding in num-- the respective pipes, a removable pipe secrtion connecting each tubeand its corresponding liquid outflow channel, means to close said pipe sections and to withdraw liquid therefrom for inspection, and a non-rotating member having a channel with which, in the rotation of thev tubes carrying the filter shaft, said liquid outflow channels successively register.

9.l A filter comprising a closed tower, a series of superimposed annular trays therein, a rotatable upright shaft in the tower, a multiplicity of filter leaves in each of said trays, a Series of sets of tubes, each setof tubes carrying the filter leaves in one of the'trays, and through which the liquid filtered by the leaves is adapted to be withdrawn, a number of vertical pipes within and rotating with the shaft and with which lthe tubes of each set communicate, and a non-rotating member having a suction channel with which said pipes successively communicate in the rotation of the shaft, means vpermitting free movement of said member in a horizontal plane for preventing rotation of the same and means to adust said non-rotating member in a circumferential direction to predetermine the points in the rotation of the shaft at which communication between said pipes and said channel are opened and closed.

10. A filter comprising a closed tower, a series of superimposed annular trays therein, a rotatable upright shaft inthe tower, filtering means carried by saidshaft and rotatable inthe several trays, a supporting framework in the topV of the tower, a member within and depending from and supported by said framework, a collar surrounding said member, said shaft being supported by and depending from said collar, and` bearings between the upper ends and lower ends of said member and collar.

11. A filter comprising a closed tower, a Series of superimposed annular trays therein, 4a rotatable upright shaft in said-tower, lfiltering means carried by said shaft and rotatable in the sev eral trays, a supporting framework in the top of said tower, a member having a spherical bear-v ing surface within and depending from and supported by said framework, va collar surrounding said member, said shaft being supported byI and jio depending from said collar, and bearings between the upper and lower ends of said member and said collar.

12. A vertical rotary valve`for a a multiplicity of filter leaves therein, which comprises a section having openings therein communicating with the filterleaves of said lter, a section having openings therein communicating j with said openings in said first mentioned section and connected with the outlets from said filters; means for producing relative rotation between saidsections; an upstanding annular lip projecting and spaced from the last named section; an annular cup secured to said lip and ex'- tending into andabove the space between the last namedsection and. the upstanding lip and filter, having spaced from both; an annular sleeve secured to the first named section and extending down into said annular cup, and a bath of mercury contained in said annular cup;

13. A filter comprising a closed tower, a series of superimposed annular trays therein, each of said trays having'partitions dividingit into arcuate filtering and filter cake removal sections,

a rotatable upright shaft extending through the tower, a multiplicity of filter leaves in each of said trays, a multiplicity of tubes carrying the filter leaves of each tray andl rotatable with the` shaft, and through which the liquid filtered through the leaves is adapted to be withdrawn, means operative during their rotation for lifting said tubes to thereby lift the filter leaves carried thereby over the partitions between the sections y of said trays, and tube driving members rotatable with the shaft and having verticalI extensions maintaining them in driving engagement with said tubes and along which the tubes are slidable in their lifting andl lowering movements.

. 1 4. A lter comprising a closed tower, a series ci superimposed annular trays therein,'each of said trays having partitions dividing it into ar.

cuate filtering and filter cake removal sections,

a rotatable upright shaft extending through the said trays, and means rotating with the shaft and independent of said mechanical connections, enf

gaging the tubes between their joints and the filter leaves, andadapted to rotate them with the shaft.

15. A filter comprising a closed tower, superimposed annular trays therein each having partitions dividing it into sections, a number of lter leaf clusters in each tray, a rotatable vertical central shaft, vertical pipes in said shaft and rotating therewith, nozzles on said shaft, ball and socket joints carried on said nozzles, tubes swingable vertically on said-ball and socket joints and communicating through said nozzles lwith said pipes, and means operative in the rotation of said shaft, pipe, nozzles, sockets and tubes, to swing said tubes vertically to lift over said partitions.

16. A filter comprising a closed tower, superimposed annular trays therein each having partitions dividing it into sections, a number of l ter leaf clusters in each tray, a rotatable vertical the filter leaf clusters central shaft,- vertical pipes in said shaft and rotating therewith, nozzles on said shaft, ball and socket joints carried onsaid nozzles, tubesswingable vertically on said ball and socket' joints and communicating through said nozzles with said pipes, and means operative in the rotation of said shaft, pipe',. nozzles, sockets and tubes, to swing `said tubes'vertically .to lift the filter leaf clusters over said partitions, vertically slidable plates through which the nozzles extend and which close openings in the shaft, and a spring between each socketjoir'it and plate holding the corresponding pipe against theshaft, each plate being slidable j vertically in the longitudinal expansion and contraction -of the pipe carrying the corresponding l nozzle.

17. A filter comprising a closed tower, superimposed annular trays therein, each having partltions dividing it into sections, a number of filter leaves in each tray,` means to rotate said filter leaves around the trays, means for lifting said vfilter leaves over the partitions in said trays,

means through which liquid filtered through the leaves is adapted to be withdrawn, means to introduce the 'mixture to be filtered t'o one section of the topmost tray andoverow means adapted to convey such mixture from one tray to the cor responding section of the next lower tray.

DANIEL B. BANKS.

PAUL D. BARTON. 

